package com.tx.test.servlet;

import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.Random;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;

public class ValidCodeServlet extends HttpServlet {

	/**
	 * 序列号
	 */
	private static final long serialVersionUID = -3225059523803947956L;
	
	public Color getRandColor(int fc, int bc) { //给定范围获得随机颜色
	     Random random = new Random();
	     if (fc > 255) {
	         fc = 255;
	     }
	     if (bc > 255) {
	         bc = 255;
	     }
	     int r = fc + random.nextInt(bc - fc);
	     int g = fc + random.nextInt(bc - fc);	
	     int b = fc + random.nextInt(bc - fc);
	     return new Color(r, g, b);
	 }
	 public void init() throws ServletException {}
	 
	 public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
	     response.setHeader("Pragma", "No-cache");
	     response.setHeader("Cache-Control", "no-cache");
	     response.setDateHeader("Expires", 0);
	     // 在内存中创建图象
	     int width = 60, height = 20;
	     BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);//对访问的图片色调为RGB格式
	     // 获取图形上下文
	     Graphics g = image.getGraphics();
	     //生成随机类
	     Random random = new Random();
	     // 设定背景色
	     g.setColor(getRandColor(200, 250));
	     g.fillRect(0, 0, width, height);   //填满
	     //设定字体
	     g.setFont(new Font("Times New Roman", Font.PLAIN, 18));
	     //画边框
	     //g.setColor(new Color());
	     //g.drawRect(0,0,width-1,height-1);
	     // 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到
	     g.setColor(getRandColor(160, 200));
	     for (int i = 0; i < 155; i++) {
	         int x = random.nextInt(width);
	         int y = random.nextInt(height);
	         int xl = random.nextInt(12);
	         int yl = random.nextInt(12);
	         g.drawLine(x, y, x + xl, y + yl);
	     }
         // 取随机产生的认证码(4位数字)
	     String sRand = "";
	     for (int i = 0; i < 4; i++) {
	         String rand = String.valueOf(random.nextInt(10));
	         sRand += rand;
	         // 将认证码显示到图象中
	         g.setColor(new Color(20 + random.nextInt(110),
	                              20 + random.nextInt(110),
	                              20 + random.nextInt(110)));
	         //调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成
	         g.drawString(rand, 13 * i + 6, 16);
	     }
	     // 将认证码存入session
	     request.getSession().setAttribute("vCode", sRand.toLowerCase());
	     
	     // 图象生效
	     g.dispose();
	     // 输出图象到页面
	     //ImageIO.write(image, "JPEG", response.getOutputStream());
	        JPEGImageEncoder encode = JPEGCodec.createJPEGEncoder(response.getOutputStream());
	        encode.encode(image);
    }

	//Clean up resources
	public void destroy() {}
	
	protected void doGet(HttpServletRequest req, HttpServletResponse resp)
			throws ServletException, IOException {
		this.doPost(req, resp);
	}
}
